Bug#617626: Status as of the ides of March.
it seems the firmware it's needed for 3d acceleration, not 'standard' graphics.
I saw several similar references to the same problem in Imac G3 that can be solved configuring Xorg with proper frequencies for the screen.
Please see the xorg.conf example in . I found more references to xorg.conf .
1 - http://lists.debian.org/debian-powerpc/2009/03/msg00081.html
2 - http://forums.debian.net/viewtopic.php?f=16&t=43326
Melhores cumprimentos/Best regards,